Formed wire fragmentation device

ABSTRACT

A formed wire fragmentation ordnance device consisting of a coiled wire casing that has been bent so as to be fluted longitudinally of the device so that said flutes form a plurality of generally concave portions connected by peaks and in which notches are provided on alternate peaks so that each concave portion will separate at one end before the other, thereby permitting end-first impact. A shaped charge at alternate peaks may be used instead of the notches. The flutes may be parallel or helical with respect to the axis of the casing and the casing may be cylindrical or oval in shape.

United States Patent [72] Inventors James C. Talley Dahlgren; Lester A. Potteiger, Fredericksburg, both of Va. [21] Appl. No. 582,800 [22] Filed Sept. 26, 1966 [45] Patented Ot .i9 i n [73] Assignee The United States of America as represented by the Secretary of the Navy 51] retina WlREi RAGMENTATION DEVICE 9 Claims, 8 Drawing Figs.

[52] US. Cl 102/67, 102/64 [51] Int. Cl F42b 13/48 [50] Field of Search 102/1, 2, 56, 64, 67, 68

[56] References Cited UNITED STATES PATENTS 29,995 9/1860 Rice 102/67 90,164 5/1869 Gibson 102/67 292,065 1/1884 Sinclair 102/91 1,203,062 10/1916 Semple 102/67 X Primary Examiner-Benjamin A. Borchelt Assistant ExaminerC. T. Jordan Att0rneys-G. J. Rubens, A. L. Branning and L. R. Radanovic ABSTRACT: A formed wire fragmentation ordnance device consisting of a coiled wire casing that has been bent so as to be fluted longitudinally of the device so that said flutes form a plurality of generally concave portions connected by peaks and in which notches are provided on alternate peaks so that each concave portion will separate at one end before the other, thereby permitting end-first impact. A shaped charge at alternate peaks may be used instead of the notches. The flutes may be parallel or helical with respect to the axis of the casing and the casing may be cylindrical or oval in shape.

PATENTEDUCT 19 Ian SHEET 10F 2 NVENTORS JAMES C. TALLEY LESTER A. P077676 AGE/VT PATENTEnnm 19 |97l SHEET 2 BF 2 FORMED WIRE FRAGMENTATION DEVICE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The invention relates generally to ordnance devices and with a more particular emphasis on fragmentation-type munitions or warheads of improved effectiveness through the use of specially formed and shaped fragments.

Presently, the fragmentation-type munition takes on a wide variety of designs, these designs being dictated by parameters such as numbers, sizes and velocities of fragments and their distribution in the space about the detonating device. These parameters have been controlled in many ways, as for example, in the manner of shaping, varying the composition and treatment of the fragmenting material, scoring of the casing, and using jet-forming explosive shapers. .Also, a commonly used technique is the assembly of preformed fragments into some sort of matrix. Fragmentation size has been controlled through the use of notched bars or wires rolled into a cylinder, the optimum sizes depending upon the nature of both the explosive charge and intended targets for the device. The varieties of fragmenting devices that have been heretofore designed and built, therefore, is quite numerous.

In all of the fragmentation-type ordnance devices, however, no attempt has been made in controlling the attitude of each segment upon detonation or in distributing the segments in the space about the detonation device so that maximum effectiveness is achieved regardless of the orientation of the device at detonation.

Accordingly, it is an object of the present invention to provide a fragmentation device wherein the attitude of the flying segments is controlled so as to project the fragments edge-on the target for maximum penetration.

Anothhr object of the present invention is to provide a fragmentation device whose casing is designed to produce, upon detonation, a substantial number of fragments with improved target penetration capability.

A further object of the present invention is to provide a formed wire fragmentation device in the form of a fluted cylinder of coiled wire such that upon disintegration thereof, a controlled number of fragments is capable of deeply penetrating light targets.

A further object of the present invention is to provide a formed wire-fragmentation warhead fluted and otherwise shaped in a manner for distributing the wire segments more unifonnly in the space about the detonating device for effecting a greater amount of target hits by the fragments.

A still further object of the present invention is to provide a formed wire-fragmentation device in the form of a helically fluted cylinder of coiled wire such that, at detonation, a significant number of fragments will effectively reach and deeply penetrate the target.

A still further object of the present invention is to provide a formed wire-fragmentation device fluted and of a generally oval shape such that, upon disintegration thereof, a significant number of segments will effectively reach and deeply penetrate the target.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of one embodiment of the formed wire fragmentation device showing flutes parallel to the longitudinal axis of the device;

FIG. 2 is a cross-sectional view taken at line 2-2 of FIG. 1 showing contoured segments between flutes;

FIG. 3 is a cross-sectional view similar to FIG. 2 showing a modification of the invention and straight segments between plates;

FIG. 4 is a perspective view of another embodiment of the fragmentation device according to the invention showing a helically fluted cylinder;

FIG. 5 is a showing of the manner in which a segment of the formed wire warhead separates upon detonation of the'device;

FIG. 6 is a perspective view of still another embodiment of the fragmentation device according to the invention of a generally oval shape;

FIG. 7 is a view in transverse cross section taken at line'7-7 ofFIG.6;and

FIG. 8 is a view in longitudinal cross section taken at line 8-8 of FIG. 6 and showing its generally oval shape.

The present device is closely related to the self-forging fragmentation device commonly known as the polygon charge described in application Ser. No. 465,804. Instead of forming long strips as in the polygon charge, the present device separates each strip into a multiplicity of 'short wire segments each with a desired contour resembling the cross section of the aforementioned device. I

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. I a formed wire'fragmentation device 10 which is generally a fluted cylinder formed of coiled wire having, for example, eight flutedsides. Detonator 11 is mounted in one of two end plates 12 which enclose the ends of the device. As is evident by reference to FIG. 2, an explosive charge 13 completely fills the enclosure defined by the coiled wire wall 14 and plates 12. The wire wall 14 may be constructed by means of two "fluted cylinders, the flutes of each arranged to intermesh when geared to'rotate about parallel axes. As the cylinders rotate, a wire, whos'e end is originally attached at a point on one end of one cylinder, is held in tension and allowed to wind in spiral fashion about one of the cylinders whose contour it is to assumeaThe second cylinder acts as a former to bend the wire down into the valleys and over the peaks of each flute. In the embodiment of FIG. 1, the flutes so formed are straight and parallel to'the longitudinal axis of the device. At the completion of the winding, the wire would have the appearance 'ofa tightly wound coil with each coil having a number of nodes with contoured segments therebetween. The forming cylinder is shaped so as to produce generally concave flutes, which may have substantially the shape of the arc of a circle, as shown in FIG. 2, or substantially the shape of an obtuse angle, as shown in FIG. 3. Peaks are formed at the intersection of adjoining flutes. When removed from the mandrel the coil would retain the exact contour of the mandrel if secured through the use of adhesive, not shown, between adjacent coils or between the inner surface of all coils and a thin metal casing, not shown, formed bn the original surface of the mandrel. The fluted, coiled cylinder thus formed is then scored as at 15 in'FlG. 2 or, as in FIG. 3, weak joints or intentional breaks are provided by the use of intemal jet-forming explosive shapers 16. In FIG. 3, it should be noted that each coil has a number of nodes with straight segments therebetween as an alternativewhich'produce the same type fragment as that shown in FIG. 2.

The fragmentation device has been designed in order to render each ring of the coil weakened as at 15 or 16, FIGS. 2 and 3, respectively, thereby assuring that, upon detonation of the charge, each ring of the coil will initially fail along joints 15 or 16, before any expansion or fracture of each ring between the joints. The casing of the instant ordnance device is fluted for the purpose of attitude control of the fragments. For example, a variation in the amount of explosive at each flute will cause the segments therebetween to accelerate at one end faster than at its other end. This, coupled with a coil weakening means or a linear shaped charge, will determine the attitude of the segment upon detonation.

As in the above-referred-to related patent application, a substantial portion of the blast energy will be released through the initial opening in the casing. The reduction of quantity of blast energy in the joint zone produces a somewhat lower acceleration at the joint end of each ring segment than at the crease end of each segment. Thereafter, the ring segments will penetrate the target while oriented in a position approaching edge-on orientation such as shown in FIG. 5 of the drawings where its crease end has travelled farther in each stage of its flight than its joint end. By varying the amount of explosive at each fluted area, the segments can in this way be made to project edge-on into the target. The wire segment fragments which are projected at high velocity from the munition will generally have a curvature along their length approaching a semicircle. These curved wires will be projected so that the planes in which they lie are coplanar with their direction of flight. Projected in this way, these wire fragments have a penetration performance which greatly exceeds that of a chunky type fragment of equal mass. A chunky-type fragment is defined as one whose distribution of mass deviates slightly from a regular cube or sphere. Most fragmenting munitions produce chunky" fragments unless designed deliberately as darts or flechettes and projected so as to fly end-on.

The reason for the increased penetration performance of the shaped wire fragments lies in the well-known fact, in penetration ballistics, that above a reasonable minimum impact velocity, penetration depends largely upon the length of the penetrator which is aligned with the direction of flight at impact. For example, a straight piece of wire travelling at high velocity would penetrate only to a depth of little more than its diameter, if it struck a flat surface flat-on. If, on the other hand, the wire struck end-on, it could penetrate to a depth equal to its length. It can be seen then, that the penetration capability of the curved semicircular piece of wire would be between these two extremes since the creased end of each fragment will travel farther than its joint end while the plane in which it lies is coplanar with its direction of flight. If desired, the wire segments, during the fabrication process of the coiled wire casing, may be of greater thickness at their joint ends than at their creased ends. In this way, a still lower acceleration at the joint end of each segment may be achieved because of the higher inertia at that end resulting from the greater wall thickness there. It can be seen, then, that the variables of wall thickness and amount of explosive thereunder can be used to control and predict the attitude of these fragments within reasonable accuracy.

In the instant device, as in the polygon device, high velocity is gained through a high ratio of explosive charge mass to projected mass. Penetration effectiveness is gained through forming and orienting the wire penetrators.

Returning to the drawings, a first modification 20 of the formed wire fragmentation device is shown in FIG. 4. Here, the device of FIG. 1 has been given a slight axial twist of approximately one-quarter turn such that the flutes are now slightly helical instead of straight. Such a design in the coiled wire device is for the purpose of distributing the wire segments more uniformly in the space about the detonating device than they would be in the untwisted case. For example, as viewed from one end and looking along the longitudinal axis of the device, there would be essentially equal numbers of wire segments projected into each small unit azimuthal angle. Because of this uniform distribution, a more significant number of wire fragments reaching and deeply penetrating the target is made possible because each segment of one ring is slightly displaced in relation to an adjacent segment of an adjacent ring. The warhead in FIG. 4 is otherwise identical to that of FIG. I, viz., the end plates 12, fuse l1 and high explosive 13.

In FIGS. 6, 7 and 8 a second modification 30 of the formed wire fragmentation device is shown as having a generally circular, fluted cross section of the same size at either end and gradually increasing in size to a maximum at the center. In longitudinal cross section, the device is outwardly bulged into an oval or elliptical shape along its length as clearly shown in FIG. 8. The purpose of such a shaped device is to widen the beam of emitted fragments in the polar direction so as to spread them more uniformly in the space about the detonating device. Uniformity in the azimuthal plane is obtained through the use of the helical twist. Spreading the beam in planes normal to the azimuthal plane is obtained by the oval or elliptical figure of revolution about the longitudinal axis. In this modification, a significant amount of emitted fragments WIII always reach the target regardless of the orientation of the device at detonation since fragments in adjacent coils do not emit parallel to each other but spread with distance from the device. The originally described method of fabrication can be used here except for the use of elliptical rather than cylindrical mandrels. Again, the warhead in this FIG. is otherwise identical to that of FIG. 1, viz, the end plates 12, fuse 11 and high explosive 13.

The use of square or rectangular wire, different charge-tomass ratios and different kinds of metal for fragments, are a few of the many parameters that may be varied. Likewise, the number of flutes may be varied, the degree of helical twist and the use of hollow versus solid charges.

From the foregoing, it can be seen that a unique type of formed wire fragmentation device has been designed such that, with a given amount of explosive charge and mass of metal to be projected as fragments, it is possible to produce a larger number of effective fragments and to control the orientation of each fragment than in the older concepts in which weights and numbers of fragments are merely controlled. In the instant invention, a particular weight of fragment can be more effective as a target penetrator because of its'shape and striking attitude than a heavier fragment of the usual chunky" type. Other advantages of this kind of fragment include lower air drag in flight and enhanced damaging ability after initial penetration.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A formed wire fragmentation ordnance device comprismg a coiled wire casing that has been bent so as to be fluted longitudinally of said casing so that said flutes form a plurality of concave portions connected by peaks; and

an explosive core within said casing.

2. The device of claim 1 in which the flutes have substantially the shape of an arc of a circle.

3. The device of claim 1 in which the flutes have substantially the shape of an obtuse angle.

4. The device of claim 1 further comprising weakening means disposed at alternate peaks, whereby the casing will be fragmented initially along said alternate peaks and subsequently along the remaining peaks so that the flutes of said coil will be made to accelerate more slowly at said alternate peaks than at said remaining peaks, whereby said segments may approach edge-on projection to deeply penetrate the target.

5. The device of claim 4 wherein the weakening means comprises notches in the wire.

6. The device of claim 4 wherein the weakening means comprises a linear shaped charge.

7. The device of claim I wherein said flutes are parallel to the longitudinal axis of said device such that said segments will be driven radially outward from said device upon detonation.

8. The device of claim I wherein said flutes are helical about the longitudinal axis of said device so as to more uniformly distribute said wire segments in the space about the ordnance device, thereby permitting equal numbers of wire segments to be projected into each small unit azimuthal angle about said device whereby the target may be more effectively reached.

9. The device of claim 1 wherein said casing is oval in longitudinal cross section, the beam of emitted fragments thereby being widened in the polar direction by spreading them uniformly in the space about the ordnance device whereby said wire fragments will effectively reach the target upon detonation regardless of the orientation of the device. 

1. A formed wire fragmentation ordnance device comprising a coiled wire casing that has been bent so as to be fluted longitudinally of said casing so that said flutes form a plurality of concave portions connected by peaks; and an explosive core within said casing.
 2. The device of claim 1 in which the flutes have substantially the shape of an arc of a circle.
 3. The device of claim 1 in which the flutes have substantially the shape of an obtuse angle.
 4. The device of claim 1 further comprising weakening means disposed at alternate peaks, whereby the casing will be fragmented initially along said alternate peaks and subsequently along the remaining peaks so that the flutes of said coil will be made to accelerate more slowly at said alternate peaks than at said remaining peaks, whereby said segments may approach edge-on projection to deeply penetrate the target.
 5. The device of claim 4 wherein the weakening means comprises notches in the wire.
 6. The device of claim 4 wherein the weakening means comprises a linear shaped charge.
 7. The device of claim 1 wherein said flutes are parallel to the longitudinal axis of said device such that said segments will be driven radially outward from said device upon detonation.
 8. The device of claim 1 wherein said flutes are helical about the longitudinal axis of said device so as to more uniformly distribute said wire segments in the space about the ordnance device, thereby permitting equal numbers of wire segments to be projected into each small unit azimuthal angle about said device whereby the target may be more effectively reached.
 9. The device of claim 1 wherein said casing is oval in longitudinal cross section, the beam of emitted fragments thereby being widened in the polar direction by spreading them uniformly in the space about the ordnance device whereby said wire fragments will effectively reach the target upon detonation regardless of the orientation of the device. 